Regenerated cellulose fibers, methods of making and using the same

Abstract

The application discloses regenerated cellulose fibers and a preparation method and application thereof, and the preparation method comprises the following steps: 1) dispersing functionalized graphene in an ionic liquid to obtain a functionalized graphene dispersion liquid; 2) mixing initial cellulose with the functionalized graphene dispersion liquid obtained in the step 1) to obtain a cellulose spinning liquid; and 3) spinning the cellulose spinning liquid obtained in the step 2) to obtain regenerated cellulose fibers; wherein the functionalized graphene is selected from at least one of amino-functionalized graphene, hydroxyl-functionalized graphene and fluorinated graphene; and the mass ratio of the functionalized graphene to the initial cellulose is 0.05-5:100. The regenerated cellulose fibers prepared by the application have relatively high breaking strength and elongation at break.

Description

TECHNICAL FIELD

[0001] The present application relates to a regenerated cellulose fiber and a preparation method and application thereof. BACKGROUND

[0002] The regenerated cellulose fiber has gradually become an important direction of green transformation of the textile industry due to its advantages of wide source, renewable, biodegradable and good biocompatibility.

[0003] The regenerated cellulose fiber has broad application prospects in many fields such as textiles, medical and health, and construction. However, the current preparation method of the regenerated cellulose fiber generally has problems of not being able to balance the strength and elongation at break, complex preparation process, high cost and the like, which limits its application in large-scale industrial production.

[0004] The traditional preparation method of the regenerated cellulose fiber, such as viscose method, can realize the regeneration of cellulose, but a large amount of toxic gas will be released in the production process, which not only harms human health but also seriously pollutes the environment. In addition, the regenerated cellulose fiber obtained by the method has low strength and elongation at break, which cannot meet the requirements of high-end textiles on material performance.

[0005] CN116590801A discloses a method for preparing a regenerated cellulose fiber by using a composite coagulation bath, which comprises: swelling cellulose in an ionic liquid; heating and dissolving the swelled raw material to obtain a spinning dope under vacuum condition; using a single solvent or a mixed solution of multiple solvents as a coagulation bath, and regenerating the regenerated cellulose fiber from the spinning dope in the coagulation bath by dry-jet wet spinning method. The breaking strength and elongation at break of the regenerated cellulose fiber obtained by the method need to be further improved.

[0006] CN106149083A discloses a functional graphene cellulose fiber prepared by a melting method and a preparation method thereof, which comprises: graphene dispersion liquid preparation, cellulose / ionic liquid mixture preparation, mixing, pre-melting, spinning dope preparation and spinning process. The cellulose fiber obtained by the preparation method has high breaking strength, but the preparation method needs pre-melting and also needs to add a dispersing agent, so the preparation process is complex.

[0007] CN109183170A discloses a preparation method of cellulose graphene composite short fibers, comprising: mixing a dispersing agent, graphene oxide and cellulose, and then dissolving them in an ionic liquid aqueous solution, wherein the addition amount of graphene oxide is 0.1-0.3wt% of cellulose, to obtain a mixed spinning dope; and the obtained mixed spinning dope is filtered, spun, coagulated, stretched, washed, bleached, oiled, cut and dried to obtain cellulose graphene composite short fibers. The breaking strength of the composite short fibers prepared by the preparation method is acceptable, but the breaking elongation still needs to be improved, and a dispersing agent needs to be added in the preparation method. CN109267164A discloses a preparation method of cellulose graphene composite long fibers. The breaking strength of the composite long fibers obtained by the preparation method is acceptable, but the breaking elongation still needs to be improved, and a dispersing agent needs to be added in the preparation method. SUMMARY

[0008] Therefore, one object of the present application is to provide a preparation method of regenerated cellulose fibers, which has both high breaking strength and breaking elongation. Another object of the present application is to provide regenerated cellulose fibers prepared by the above-mentioned preparation method. Still another object of the present application is to provide an application of the above-mentioned regenerated cellulose fibers.

[0009] The above objects are achieved by the present application which adopts the following technical solutions.

[0010] In one aspect, the present application provides a preparation method of regenerated cellulose fibers, comprising the following steps:

[0011] 1) dispersing functionalized graphene in an ionic liquid to obtain a functionalized graphene dispersion;

[0012] 2) mixing initial cellulose with the functionalized graphene dispersion obtained in step 1) to obtain a cellulose spinning dope;

[0013] 3) spinning the cellulose spinning dope obtained in step 2) to obtain regenerated cellulose fibers;

[0014] wherein the functionalized graphene is selected from at least one of amino-functionalized graphene, hydroxyl-functionalized graphene and fluorinated graphene;

[0015] wherein the initial cellulose is selected from wood pulp cellulose and / or cotton pulp cellulose;

[0016] wherein the mass ratio of the functionalized graphene to the initial cellulose is 0.05-5:100.

[0017] According to the preparation method, preferably, in step 1), the mass ratio of the functionalized graphene to the ionic liquid is 0.003-0.015:40-60.

[0018] According to the preparation method, preferably, the ionic liquid is an imidazole ionic liquid.

[0019] According to the preparation method, preferably, the ionic liquid is one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium chloride.

[0020] According to the preparation method, preferably, the ionic liquid is 1-allyl-3-methylimidazolium chloride.

[0021] According to the preparation method, preferably, the mass ratio of the functionalized graphene to the initial cellulose is 0.1-1:100; and in step 2), the temperature during mixing is 40-85℃.

[0022] According to the preparation method, preferably, in steps 1) and 2), no dispersant is added.

[0023] According to the preparation method, preferably, in step 3), the cellulose spinning solution obtained in step 2) is defoamed, the defoamed cellulose spinning solution is sprayed through a spinneret, shaped in a coagulation bath, then washed with water, dried and oiled to obtain the regenerated cellulose fiber.

[0024] In another aspect, the present application further provides a regenerated cellulose fiber prepared according to the preparation method.

[0025] In still another aspect, the present application further provides a use of the regenerated cellulose fiber according to the above in the preparation of carbon fibers.

[0026] The regenerated cellulose fiber prepared by the preparation method has both high breaking strength and high elongation at break. The breaking strength can be up to 2.75 cN / dtex or higher, and the elongation at break can be up to 8.10% or higher. In addition, the preparation method does not need to add any dispersant, does not need to be pre-melted, and does not need high temperature, and the process is simpler. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 SEM image of the regenerated cellulose fiber obtained in Example 1.

[0028] Figure 2 SEM image of the wood pulp cellulose (i.e. initial cellulose) used in Example 1. DETAILED DESCRIPTION

[0029] The application will be further described in connection with specific examples, but the scope of the application is not limited thereto.

[0030] The method for preparing the regenerated cellulose fiber of the present application comprises the following steps: (1) a functionalized graphene dispersion liquid forming step; (2) a cellulose spinning liquid forming step; (3) a spinning step. The following will be described in detail.

[0031] <Functionalized graphene dispersion liquid forming step>

[0032] The functionalized graphene is dispersed in the ionic liquid to obtain a functionalized graphene dispersion liquid. The present application surprisingly finds that the use of functionalized graphene is conducive to the improvement of both the breaking strength and the breaking elongation, and the present application further finds that the functionalized graphene is first dispersed in the ionic liquid to form a dispersion liquid, and then mixed with the initial cellulose, which is more conducive to the improvement of the breaking strength and the breaking elongation. The person skilled in the art knows that it is not easy to simultaneously improve the breaking strength and the breaking elongation.

[0033] In the present application, the functionalized graphene is selected from at least one of amino-functionalized graphene, hydroxyl-functionalized graphene and fluorinated graphene, preferably one of amino-functionalized graphene, hydroxyl-functionalized graphene and fluorinated graphene, and more preferably one of amino-functionalized graphene and hydroxyl-functionalized graphene. The amino-functionalized graphene, the hydroxyl-functionalized graphene and the fluorinated graphene can be commercially available.

[0034] In the present application, the mass ratio of the functionalized graphene to the ionic liquid is 0.003-0.015:40-60, preferably 0.003-0.015:50, and more preferably 0.005-0.01:50.

[0035] In the present application, the ionic liquid is an imidazole ionic liquid. Preferably, the ionic liquid is selected from one of 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium chloride. More preferably, the ionic liquid is 1-allyl-3-methylimidazolium chloride.

[0036] In the present application, the dispersion of the functionalized graphene in the ionic liquid specifically comprises the following steps: the functionalized graphene and the ionic liquid are mixed by stirring at 40-85°C and 300-1000 rpm for 0.5-1.5 h, so that the functionalized graphene is uniformly dispersed in the ionic liquid. The temperature during mixing is preferably 50-80°C, and more preferably 70-80°C. The stirring speed is preferably 350-800 rpm, and more preferably 350-500 rpm. The mixing time is preferably 1-1.5 h.

[0037] In this step of the present application, no dispersant is added.

[0038] <Formation step of cellulose spinning solution>

[0039] The initial cellulose is mixed with the obtained functionalized graphene dispersion to obtain a cellulose spinning solution. This is advantageous for improving both the breaking strength and the breaking elongation.

[0040] In the present application, the initial cellulose can be selected from wood pulp cellulose and / or cotton pulp cellulose. The wood pulp cellulose or cotton pulp cellulose can be commercially available. The degree of polymerization of the wood pulp cellulose or cotton pulp cellulose can be 200-1000, preferably 200-800, more preferably 400-800, and even more preferably 600-750.

[0041] In the present application, the mass ratio of the functionalized graphene to the initial cellulose is 0.05-5:100, preferably 0.1-1:100, more preferably 0.1-0.5:100, even more preferably 0.25-0.5:100, and further preferably 0.3-0.5:100. For example, it can be 0.1:100, 0.15:100, 0.25:100, 0.3:100, 0.35:100, 0.4:100, or 0.5:100. The regenerated cellulose fiber thus obtained can have both a high breaking strength and a high breaking elongation.

[0042] In the present application, the step of mixing the initial cellulose with the obtained functionalized graphene dispersion specifically includes stirring and mixing the initial cellulose with the obtained functionalized graphene dispersion at 40-85°C and 300-1000 rpm for 1-3 h, so that the initial cellulose is fully dissolved in the functionalized graphene dispersion to obtain a cellulose spinning solution. The temperature during mixing can be 40-85°C, preferably 50-80°C, and more preferably 70-80°C. The stirring speed can be 300-1000 rpm, preferably 350-850 rpm, and more preferably 350-550 rpm. The mixing time can be 1-3 h, preferably 1-2.5 h, and more preferably 1.5-2 h.

[0043] In this step of the present application, no dispersant is added.

[0044] <Spinning step>

[0045] The obtained cellulose spinning solution is spun to obtain a regenerated cellulose fiber. This is advantageous for obtaining a regenerated cellulose fiber with stable performance.

[0046] In some specific embodiments, the obtained cellulose spinning solution is defoamed, the defoamed cellulose spinning solution is sprayed out of a spinneret, formed in a coagulation bath, then washed with water, dried and oiled to obtain regenerated cellulose fibers.

[0047] In the present application, the defoaming can be under vacuum standing. The cellulose spinning solution can be delivered by a metering pump to the spinneret which is 1-3 cm away from the coagulation bath. The coagulation bath can be a water bath or an aqueous solution of ionic liquid. In some embodiments, the coagulation bath is a water bath.

[0048] The drying can be natural air drying, and the drying temperature can be 25-40℃.

[0049] It is believed in the present application that in the preparation method of the present application, the ionic liquid and the specific functionalized graphene exert a synergistic lubricating effect, which significantly improves the flowability of the cellulose spinning solution, lays a foundation for the uniform formation and excellent performance of the regenerated cellulose fibers. Meanwhile, the amino, hydroxyl or fluorine groups in the functionalized graphene can form hydrogen bonds with the hydroxyl groups of cellulose, and a strong interaction is formed through the hydrogen bonds, which not only enhances the internal structure of the regenerated cellulose fibers, but also significantly improves the breaking strength and elongation at break of the regenerated cellulose fibers.

[0050] The present application also provides a regenerated cellulose fiber prepared according to the preparation method as described above. It has a relatively high breaking strength and elongation at break. The breaking strength can be 2.60 cN / dtex or more, preferably 2.75 cN / dtex or more, and more preferably 2.89 cN / dtex or more. The elongation at break can be 7.40% or more, preferably 8.10% or more, and more preferably 8.50% or more.

[0051] The regenerated cellulose fiber of the present application can be used to prepare carbon fibers.

[0052] The test methods used in the following examples are described as follows:

[0053] SEM test: using a scanning electron microscope (SEM500) produced by ZEISS Company of Germany.

[0054] Breaking strength test: according to (GB / T14337-2008), the tensile speed of the electronic single fiber strength tester is set to 50 mm / min, the return speed is 80 mm / min, the initial tension value is 10 cN, the clamp distance is 10 mm, the experimental temperature is 25℃, and the experimental relative humidity is 40BH%. The fibers to be tested are dried in a 50℃ oven for 2 hours, and the breaking strength and elongation at break of the fibers are measured by the electronic single fiber strength tester.

[0055] The raw materials used in the following examples are described as follows:

[0056] Wood pulp cellulose was provided by Shandong Hailong Co., Ltd., with a degree of polymerization of 702, which was ground into 49-297 pm by a high-speed grinder. 1-allyl-3-methylimidazolium chloride (CAS: 65039-10-3) was purchased from Beijing Mai Ruida Technology Co., Ltd. Aminated graphene was purchased from Tianjin Ailian Electronic Technology Co., Ltd. Fluorinated graphene was purchased from Tianjin Ailian Electronic Technology Co., Ltd. Hydroxylated graphene was purchased from Anhui Zesheng Technology Co., Ltd.

[0057] Example 1

[0058] The aminated graphene and 1-allyl-3-methylimidazolium chloride ionic liquid were mixed under stirring at 70°C and 500 rpm for 1 h, so that the aminated graphene was uniformly dispersed in the 1-allyl-3-methylimidazolium chloride ionic liquid to obtain a functionalized graphene dispersion. The mass ratio of the aminated graphene to the 1-allyl-3-methylimidazolium chloride ionic liquid was 0.003:50.

[0059] The wood pulp cellulose (i.e., the initial cellulose) and the obtained functionalized graphene dispersion were mixed under stirring at 70°C and 500 rpm for 1 h, so that the wood pulp cellulose was fully dissolved in the functionalized graphene dispersion to obtain a cellulose spinning solution. The mass ratio of the aminated graphene to the wood pulp cellulose was 0.1:100.

[0060] The cellulose spinning solution was deaerated in a vacuum drying box, and then the deaerated cellulose spinning solution was transported by a metering pump to a nozzle at a distance of 1-3 cm from a coagulation bath. The deaerated cellulose spinning solution was sprayed out of the nozzle and formed in the coagulation bath, and then was washed with water, dried, and oiled to obtain regenerated cellulose fibers. The SEM image of the obtained regenerated cellulose fibers is shown in Figure 1 , and the SEM image of the wood pulp cellulose (i.e., the initial cellulose) is shown in Figure 2 . The performance test data of the obtained regenerated cellulose fibers are shown in Table 1.

[0061] Example 2

[0062] The same as Example 1 except for the following parameter settings: in this example, the mass ratio of the aminated graphene to the wood pulp cellulose was 0.25:100. The performance test data of the obtained regenerated cellulose fibers are shown in Table 1.

[0063] Example 3

[0064] The same as Example 1 except for the following parameter settings: in this example, the mass ratio of the aminated graphene to the wood pulp cellulose was 0.3:100. The performance test data of the obtained regenerated cellulose fibers are shown in Table 1.

[0065] Example 4

[0066] Except for the following parameter settings, the rest is the same as example 1: in this example, the mass ratio of aminated graphene to wood pulp cellulose is 0.4:100. The performance test data of the obtained regenerated cellulose fibers are shown in Table 1.

[0067] Example 5

[0068] Except for the following parameter settings, the rest is the same as example 1: in this example, the mass ratio of aminated graphene to wood pulp cellulose is 0.5:100. The performance test data of the obtained regenerated cellulose fibers are shown in Table 1.

[0069] Table 1

[0070]

[0071] Example 6

[0072] Except for the following parameter settings, the rest is the same as example 1: aminated graphene is replaced by hydroxylated graphene; the mass ratio of hydroxylated graphene to wood pulp cellulose is 0.2:100. The performance test data of the obtained regenerated cellulose fibers are shown in Table 2.

[0073] Example 7

[0074] Except for the following parameter settings, the rest is the same as example 1: aminated graphene is replaced by fluorinated graphene; the mass ratio of fluorinated graphene to wood pulp cellulose is 0.2:100. The performance test data of the obtained regenerated cellulose fibers are shown in Table 2.

[0075] Comparative Example 1

[0076] Except for the following parameter settings, the rest is the same as example 6: hydroxylated graphene is replaced by graphene. The performance test data of the obtained regenerated cellulose fibers are shown in Table 2.

[0077] Table 2

[0078]

[0079] As can be seen from Table 1 and Table 2, the regenerated cellulose fibers obtained by the present application have relatively high breaking strength and elongation at break.

[0080] The present application is not limited to the above-mentioned embodiments, and any modification, improvement, or replacement that can be conceived by those skilled in the art without departing from the essential content of the present application falls within the scope of the present application.

Claims

1. A method for preparing regenerated cellulose fibers, characterized in that, Includes the following steps: 1) Functionalized graphene is dispersed in an ionic liquid to obtain a functionalized graphene dispersion. 2) Mix the initial cellulose with the functionalized graphene dispersion obtained in step 1) to obtain the cellulose spinning solution; 3) Spin the cellulose spinning solution obtained in step 2) to obtain regenerated cellulose fibers; Wherein, the functionalized graphene is amino-based graphene; and the ionic liquid is 1-allyl-3-methylimidazolium chloride. The initial cellulose is selected from wood pulp cellulose and / or cotton pulp cellulose; The mass ratio of the functionalized graphene to the initial cellulose is 0.4–0.5:

100.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass ratio of the functionalized graphene to the ionic liquid is 0.003-0.015:40-60.

3. The preparation method according to claim 1, characterized in that, In step 2), the mixing temperature is 40–85°C.

4. The preparation method according to claim 1, characterized in that, No dispersant was added in either step 1) or step 2).

5. The preparation method according to claim 1, characterized in that, In step 3), the cellulose spinning solution obtained in step 2) is degassed, and the degassed cellulose spinning solution is sprayed out through a spinneret, formed in a coagulation bath, and then washed, dried and oiled to obtain regenerated cellulose fibers.

6. A regenerated cellulose fiber, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 5.

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